1. Technical Field
This invention relates to a physiologically active substance, which is water-soluble derived from yeast cell walls, to its production and to a chemotherapeutic agent such as a carcinostatic or antitumor agent and an interferon inducer.
2. Prior Art
A number of the processes for production of carcinostatic substances from yeast cells have been known, most of which comprise subjecting yeast cells to hot water treatment, alkali treatment or autolysis treatment and obtaining water-soluble carcinostatic substances from the solution fractions. These processes, however, have low degree of utilization of yeast cells, and are also accompanied by problems such as that of waste water, which are not negligible.
The processes for obtaining carcinostatic substances from yeast cell walls themselves are described, for example, in Japanese Patent Publication No. 15712/1972 and Japanese Laid-open Patent Publication No. 44614/1978. The former invention comprises subjecting a specified yeast to treatments consisting essentially of autolysis, enzymatic treatment and warm weak-alkaline treatment, collecting the resulting cell wall fraction, and subjecting the fraction to strong-alkaline treatment under heat. The latter invention comprises using as an antitumor agent a water-insoluble fraction which has been obtained by removing a water-soluble extract from the autolysis product from brewer's yeasts. The latter carcinostatic substance is, of course, water-insoluble. The carcinostatic substance obtained by the former process is described as being water-soluble and being a carcinostatic high-molecular polysaccharide consisting of only glucose. The substance, however, is gelled in neutral water or an acidic water, and the gelled substance is soluble in an alkaline water (cf. Col. 3, lines 33 through 36 of the Publication).
The carcinostatic activities of these carcinostatic substances derived from yeast cells are described only for the case on Sarcoma 180 solid tumor of mice where the substances are administered intraperitoneally to the mice. The details of the effects on other tumors and/or other routes of administration of the substances are not clear.